This study explores how young children appropriate school rules and what opportunities for active participation are afforded in a Reggio Emilia elementary classroom with particular interest in the interactional and communicative competences children display in situated practice. An ethnographic and microanalytic approach is used to study how the material environment and multimodal resources are mobilized in the activity. The analysis is based on video-recorded sequences in which 6- to 7-year-old children participate in a school project about rules for the schoolyard. The detailed analysis demonstrates how the children plan, reflect, enact, and discuss how to apply their own co-constructed rules in locally relevant ways in the playground. Overall, the findings shed light on how opportunities for children's active participation are situated within and also afforded by the particular Reggio Emilia educational practice that is also shaped by the learning process itself. (Contains 1 figure, 5 excerpts and 1 footnote.)